Nope. That's perfectly legitimate too, and it's been part of my toraining, and I've complimented serving officers on handling situations I've seen develop around them when they've done exactly that. It's amazing to see how drivers treat someone on a motorcycle who is doing 30mph in a 30mph zone when they don't know that the motorcyclist is a police officer because he's on his own bike in his civvy gear. You just know they'd never do that if the guy was on a marked bike.
If an aggressive driver presents a potential hazard, and there's nowhere else for you to go, then you have no alternative but to take control of the situation. If you can just get out of there it will usually be a better alternative, but sometimes there is no alternative. I'm not talking about treating aggression with aggression, or pointlessly irritating people who are already on the edge. Mostly I'm talking about giving out information. If somebody gets pushy with me on the road, the information I give lets them know that I'm in control. Not out of control.
It sounds like you're misleading my post. Did you read the entire thing? slowing down to annoy a tailgater or even moving over really slowly is bad driving. The aggressor is driving badly but so is the driver who is defending his right to be on the road. It semantics.